Movable agricultural irrigation systems such as center-pivot and linear systems are commonly used to irrigate large fields and typically include a conduit extending across several irrigation spans. Each irrigation span supports a conduit section elevated on a support tower including wheel assemblies configured to traverse a path along the ground for moving the conduit across the fields. The wheel assemblies may include conventional pneumatic tires or “airless” tires. In the airless tire embodiments, the wheel assemblies typically include a rigid wheel and an airless flexible tire mounted thereon. The rigid wheel has spaced apart outwardly protruding spokes so as to form a polygon shape or other non-circular shape. The airless flexible tire has rigid sections aligned with the outwardly protruding spokes and flexible sections configured to be deflected inwardly between the outwardly protruding spokes when the flexible sections engage the ground. The airless flexible tire exerts higher torque on the ground near the outwardly protruding spokes. However, in certain applications and field conditions, a lower maximum torque or a more evenly distributed torque profile is desired. Switching out wheel assemblies according to the desired maximum torque or torque profile is highly impractical and prohibitively expensive even if the change is permanent. For this reason, farmers usually opt to continue using the high torque wheel assemblies. This results in excessive field wear and fatigue on the drive motor and other moving parts of the irrigation spans.